Process and apparatus for stretching continuous sheet materials



Filed Dec. 14, 1946 April 25, 1950 w. H. RYAN 2,505,146 PROCESS AND APPARATUS FOR STRETCHING '7 CQNTINUOUS SHEET MATERIALS 9 Sheets-Sheet 1 P2 1NVENTOR Aprll 25, 1950 w. H. RYAN 2,505,146

- PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS Filed Dec. 14, I946 9 Sheets-Sheet 2 FIG. 2

INV NTOR Apnl 25, 1950 w. H. RYAN 2,505,146

PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS Filed Dec. 14, 1946 9 Sheets-Sheet 3 FIG. 3

INVENTOR April 25, 2,505,146

W. H. RYAN PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS Filed Dec. 14, 1946 9 Sheets-Sheet 4 Sire'rch Area Axis of inpui IOHSw Axis of ourpul' rolls Pufh of Ourgoing Sheefing April 25, 1950 Filed Dec. 14, 1946 W. H. RYAN PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS *9 Sheets-Sheet 5 INVENTOR Apnl 25, 1950 w. H. RYAN 2,505,146

PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS Filed Dec. 14, 1946 9 Sheets-Sheet 6 INVENTOR jmauw April 25, 1950 w H RYAN 2,505,146

PROCESS AND APiAR ATUS FOR STRETCHING CONTINUOUS SHEET MATERIALS filed Deg 14, 1946 9 Sheets-Sheet 7 FIG. H

is variable FIG. l2

a( 90 90 and is variable (22 j FIG. \3

GOIZ

c4 and \l or: variable INVENTOR April 25,.1950 w. H. RYAN 2,505,146

PROCESS AND APPARATUS FOR STRETCHING CONTINUOUS MATERIALS Filed Dec. 14, 1946 9 Sheets-SheetB -I4OO variable d. and are o(-ond\/ do no? individually April 25, 1950 w :H. RYAN 2,505,146

PROCESS AND AP-hARA'rus FOR STRETCHING cou'rmuous SHEET MATERIALS h 9 Sheets-Sheet 9 Filed Dec. 14, 1946 G (My) Machine Machine 2 lnpuf Section N, and 1 are all vqriablz j INVENTOR FIG. I? BY 3 Patented Apr. 25, 1950 UNITED STATES PATENT OFFICE PROCESS AND APPARATUS FOR STRETCH- ING CONTINUOUS SHEET MATERIALS William H. Ryan, Cambridge, Mass., assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Application December 14, 1946, Serial No. 716,308

22 Claims. (Cl. 18-1) This invention relates to continuous processes and apparatus for stretching continuous sheet materials as well as to products formed in the practice of such processes.

Objects of the invention are to provide novel processes for stretching continuous sheet materials whereby to predeterminedly modify the characteristics and properties thereof and also to provide processes for forming novel products making use of predeterminedly modified, continuous sheet material.

Another object of the invention is to provide a stretching process involving moving continuous sheeting lengthwise of itself along a selected path and at a selected speed and discharging it at a substantially straight line which extends across such path and which lies in a, predetermined plane and applying pressure to the sheetingby the application of a frictional force to the surfaces thereof substantially along the discharge line while continuing the lengthwise movement of the sheeting without interruption by drawing it under tension at a second selected speed along a second selected path and against th restraining frictional force applied to the sheeting, the traces of the selected paths when projected into the plane of the discharge line appearing as straight lines which are angularly disposed to the discharge line in such relation that the trace of one path is disposed at angles of other than 90 to the discharge line.

Other objects of the invention are the provision of processes wherein stretching is employed to alter dimensions of sheet materials and to alter the area of sheet materials, as well as in the provision of processes for predeterminedly stretching sheet materials in a direction inclined to the longitudinal edge of such materials and also to predeterminedly orient the molecules of sheet v material and especially to orient the molecules of sheet material in a direction angularly disposed to the longitudinal edges thereof.

Yet other objects of the invention are to provide processes of the nature described, wherein 2 or bonded to other continuous sheet material in superposed relation thereto.

Yet further objects of the invention are to provide apparatus and means for stretching continuous sheeting and laminating it to other sheeting whereby to carry out stretching processes of the character described; to provide apparatus for stretching continuous sheeting wherein sheeting is moved along a selected path in a selected direction and wherein the sheeting is placed under tension while continuing its movement along a second selected path at a second selected speed; to provide apparatus of the character described having means engaging and moving continuous sheeting lengthwise of itself along a selected path at a selected speed and discharging it at a straight line which extends across such path and which lies in a predetermined plane, the apparatus having means for applying pressure to said sheeting along said discharge line and also having means engaging the sheeting and continuing the lengthwise movement thereof without interruption by drawing it under tension at a second selected speed along a second selected path and against the force applied thereto at the discharge line, the traces, in the plane of the discharge line, of the paths followed by the sheeting being in predetermined relation to the discharge line and especially in a relation such that at least the trace of one path is disposed to the discharge line at angles of other than 90; and to provide means in a machine of the character described for changing the direction of the paths followed by sheeting in its movement through the machine as well as to provide means for moving the sheeting at selected speeds along said paths.

Still other objects reside in the provision of stretching apparatus comprising spaced-apart input rolls and output rolls and means associated with said rolls whereby sheet material may be passed therethrough while following paths which are in predetermined angular relation to the axes of the input rolls and the output rolls; to provide, in apparatus of the character described, means for causing sheeting to be fed into and passed through pressed-together rotating rolls while following selected paths lying in predetermined directions, especially driven belt means for causing the moving sheeting to track or follow a predetermined path; and also to provide stretching apparatus having an input section and an output section in at least one of which sections means are employed for moving the'sheeting undergoing chine of the character described or a plurality of such machines arranged .in pairsfor successively operating upon continuous sheetingwhereby to predeterminedly modify the sheeting; to provide individual machines with means for softening sheeting undergoing :pro'ce'ssing'to fa- I cilitate the stretching thereof; and also to provide means adapted to reharden the softened sheeting after stretching as well as means to predeterminedly cut the sheeting.

Other objects of the invention will in part be :.obvious and will in-part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and the order of one or more of such steps with respectto each of the others, the products produced by said processes .andpossessing the features, properties and the relation of components, and the apparatus possessing the construction, combination. of elements and arrangement of parts which are exemplified :in the following. detailed disclosure; and thescope of the application of which will be indicatedin theclaims.

For a fuller understanding of the nature and objects ofthe invention,-reference should be had tion of a portion of the machine illustrated in Figs. 1,2 and 3; V I v Fig. 3 is an endelevation ofthe apparatus of Fig. 1 with parts thereof omitted;

Fig. 4 is a diagrammatic plan view of "the machine of Figs. 1, 2 and '3 and shows the path of movement of the sheet material through the machine;

Fig. 5 is a detail elevation or a roll support used ina part of the apparatus;

"Fig. 6 is a partial elevation of a conveyor'belt used with the machine;

Fig/7 is an elevation of a heating duct'em- .ployed with the apparatus;

Fig. '8 is asection on'the line 8-8 of Fig. '7;

Fig. '9 is a vertical sectionsimilar to Fig. 2 of amodified portion of stretching apparatus with parts of the machine brokenxaway and omitted;

Fig. 10 is a plan view showing another embodiment of stretching apparatuswith parts omitted for the sake of clarity;

Figs. 11, 12, 13 and 14 are schematic illustrations in plan of possible arrangements of setup for machines of the inventionwith each figure showing the path direction of-movement of sheeting through such a machine and with Figs. 11-, 12 and 13 illustrating special cases of machine setupwhich follow from thegeneral case of machine setup disclosed in Fig. 14;

-Figs. 15 and 16 arerespectively-schematicplan views of unprocessed sheeting'incoming intoa machine of the invention and processed sheeting outgoing from such machine;

Fig. 1'7 is a schematic plan view of a plurality of machines of the character of the machine of Figs. 10 and 14 arranged in series and showing the path direction followed by sheeting in movement therethrough; and

Fig. 18 illustrates a product of the invention in the form of motion picture film material.

-'I It is known that the physical characteristics of many solid materials'may be changed by stretchfingsuch materials. For example, a material may be stretched to' increase its tensile strength in a direction parallel to the direction of stretch. A

--=sheet material maybe stretched for the purpose 1 of increasing its area or for changing its dimensionsasrby increasing its length or its width or for-the purpose of flattening the sheet.

in -loss of materials.

by decreasing its thickness or its width as well In the case of a plastic sheet, stretching may be employedto orient its molecules or to increase the birefringence of the sheet.

Plastic sheet materials .which are hydrophilic as well as those which are substantially nonhy- :drophilic or arehydrophobic and which have long chain, substantially-oriented molecules are .useful'for numerous purposes. For example, oriented plastic sheet materials may be employed in the formation of:a variety of optical elements such as polarizerspfilters, spectacle and goggle lenses, wave retardation elements, headlights, Windshields, and the like. Also, suitable materials of this character may be'used-in photography in the formation of a light-polarizing sheet which serves as a support or carrier for a light-sensitive emulsion and in addition transparent, hydrophilic, molecularly oriented plastic material is Well adapted for the formation or reproduction therein of light-polarizing images, designs, and the like. In all of these .uses,1hydrophilic, molecularly oriented material may have one or more dichroic substances, such as a dichroic stain or dye, incorporated throughout the same or only in predetermined portions thereof to render those portions of the material which contain the ,dichroic stain or dye light-polarizing in character.

For many purposes it has been found more advantageous and convenient to'effect an orientation of the molecules of plastic sheeting in some direction other than lengthwise or longitudinally of the sheeting. For example, inthe formation ofvectog'raphs, a moleculari'orientation making an angle of to the longitudinal edge of the t sheet is desirable. It is also expedient to employ .an orientation axis of 45 or of 35or of 22 for usein polarizing headlights-these angles being measured from a longitudinal edgeo'f sheeting which is employed'for .this purpose.

-Plastic sheet material having its molecules oriented longitudina'll' ofthe sheet; or for that matter oriented laterally or" the sheet, may be cut at an angle'to the-edge'of the sheet to provide one or more rectangles having the preferred orientation axes of 45 'or'35'or-22 /2. However, such practice is wasteful, not only in labor but When sheet material is cut as just described, only relatively short lengths of a maximum of several feet can be obtained. It is-' obviously impracticalto secure or splice these 'shortpicces-together to provide continuous sheeting as, for example, in even or IOU-foot lengths suitable for the production of amateur motion picture film, l'et alone in lengths of 1,000 and-2,000 feet-neededin-rorming 35 motion ascents:

picture film in standard reel lengths. Furthermore, pieces of sheet material having a molecular orientation at an angle of other than 90 to an edge thereof, at present made available by suitably cutting longitudinally or laterally stretched sheeting, are of insufficient length for automobile windshield work without splicing, a condition which is, of course, undesirable.

, The desirability of providing a process and apparatus for stretching continuous plastic sheet material whereby to orient its molecules in a predetermined transverse direction of the sheet or in a direction inclined to the long edge of the sheet at a predetermined angle will be appreciated, especially when the process and apparatus may be employed to control the degree of orientation of the molecules.

"lo this end the invention contemplates the provision of processes and apparatus for continuously stretching sheet material which involves moving continuous sheeting lengthwis of itself along a selected path at a selected speed towards a straight line which extends across such path and which lies in a predetermined plane, discharging the sheeting across said line while applying a frictional force to the surfaces of the sheeting whereby to exert pressure on the sheeting in a direction substantially perpendicular to its surfaces along the discharge line and continuing the lengthwise movement of the sheeting without interruption by drawing it under tension at a second selected speed along a second selected path and against the restraining frictional force applied along the discharge line.

Stretching to effect orientation in a direction inclined to an edge of the sheeting is so carried out that the traces of the paths along which the sheeting moves, when projected into a plane which contains the discharge line, appear as straight lines which are angularly disposed to the discharge line in such relation that the trace of at least one path is disposed at angles of other than 90 to the discharge line. This plane which contains the discharge line is commonly referred to as the plane of the discharge line. By such procedure the traces of the two paths in the plane of the discharge line are angularly disposed with respect to each other. It is also possible, as will presently appear, to conduct stretching operations in such manner that the second selected path forms a continuation of the first path followed by the sheeting in its movement so that traces of the two paths in the plane of the discharge line form a substantially straight line.

'When sheet material is stretch processed in the manner just described, the forces set up in the sheeting as it moves along the just-mentioned paths, at least in the case of plastic materials, effect an orientation of its molecules. The rate of speed at which the sheet material is incoming towards the discharge line and the rate of speed at which it is outgoing from the discharge line, subsequently described as the speed ratio u, as well as the angular relation of the paths followed by the sheeting with respect to the discharge line, hereinafter described as the input angle a and the output angle will determin the angular direction of the orientation of the molecules of the sheeting with respect to a longitudinal edge of the sheet'material, hereinafter designated by the angle t and called the orientation axis, as well as the degree of orientation of the molecules, hereinafter designated by K and called the axial ratio. .While sheet materials other than plastic sheeting may be treated by the machines and 6 processes set forth herein, operations upon plas tic sheeting afford excellent examples for illustrating the invention and the machines and processes thereof will be described primarily in connection with the treatment of plastic sheeting.

Orientation of the molecules of plastic sheet. materials occurs as an incident to the stretching of such materials. The terms molecular orientation, orientation, molecularly oriented, and oriented as used in the specification and claims with reference to sheet materials, unless other-.

' also possible to orient the molecules of sheet mawith respect to each other.

terials so that the long axis of each molecule is substantially parallel to the plane which passes through the length and breadth dimensions of the sheet and whereby the long axes of the mole-. cules are otherwise heterogeneously arranged This latter type of orientation is known as uniplanar orientation and the same may be obtained by the processes and machines described herein and when so obtained will be specifically indicated.

To carry the invention into effect, use is made of an apparatus or machine having an input section wherein sheet material is continuously fed or moved along a selected path towards an adjoining output section where its movement is continued along a second path while placing the material under tension, the various parts of the machine being supported from the floor. In this arrangement, intersection of the paths followed: by the incoming and outgoing sheeting occurs at the junction of the input and output sections.

One embodiment of such a machine is shown in Figs. 1, 2 and 3 and primary elements thereof comprise aligned input or belt rolls 43 and 44 in conjunction with driven belt means 24 which pass over these rolls and pressure-applying means 25 for pressing the rolls and belt means together, all located in the input section of the machine, and a pair of pressed-together and aligned output rolls 26 located in the output section of the machine and spaced from the input rolls 43. The various parts of the machine are mounted upon a stand or table 20.

Rolls 43 and 44 in conjunction with driven belt means 24 engage sheeting 22 from the stock roll 23 to move the sheeting lengthwise of itself in a predetermined direction with respect to the line of tangency of belt means 24 at the rolls 43 and 44 and effect a continuous discharge of the sheet material at a fixed location along such line of tangency into the output section of the machine. The common ends of the input and output sec-- tions may be thought of as determined by the lineof tangency between the belt means 24 passing over the rolls 43 and 44.

A more detailed description of the belt means and its function will subsequently appear.

The pressure-applying means 25 permit the belt means 24 and rolls 43 and 44 to apply frictional force to the surfaces of the sheeting in a direction substantially perpendicular to such surfaces along the line of tangency between the belt means going over the rolls 43, 44, which line thus becomes a pressure-applying line extending across the path of the sheeting incoming to the inputcrolls as well as a line of discharge rann es:

lelztotheaxesiof rolls lSzand 44;:it1wil1;never thelessbe. appreciated-..thatz the-adirection: of the;

path. along which; the: sheeting moves. from the;

lineofztangencymi the beltzmeans: .24 to the-draw lug-rolls 2 6:" is angularly. disposed. with; respect to the direction of"the"path;followedbyrthe sheeting in theinput sectioirof thexmachine Figs. 1 2,. and 3: However, as it...will be v subsequently. pointed out, it:is-unnecessary for the :axes of rolls:

26 to be in parallel relationto the axes .ofrolls 43: and.

()ther elements of': the: apparatuslocated, in the output-section and which willbe later'de scribediin: detail comprise means. 21' for soften:

ing. thesheeting whereby to increase its ductility,

rolls 28 locatedina sheet? hardening zone and over which the stretched and drawn sheetx22:is,

moved; means 29.:foncutting the sheeting 22110 a. predetermined width, laminating .means 30 whioh draw the sheeting: 22.1together; with asecond; sheeting 3-1; the latter; being carried one-supply roll 32; length-wisesof" themselves. into contact.-

with each othertolaminate the-sheeting 3| and; 22.1 together, and ifde'sired'reeling or winding means 33iior winding the laminated. sheeting'34' into a roll; suitable source. of electricity-is employedfor: driving: the belt. means and the rotating drawing rolls of *themachine in a mannerstobeJaterrde:- scribed;

Assume a pair of:rotating wringer..rol1s are-- ranged in pressure. contact to haveptheir axes .of

rotation substantiallyparallel; When sheetingjs;

fed between such-apairroffrolls sothat azlongie tudinal edge-thereof fcrmsanacute angle-which lies outside of the sheet-and which is formed between-such edge and thezline of tangency. of the rolls, the sheeting; during; its: passage; between. the?rollsiranslateswith respectato' the: line of tangency in the. general direction :of the slope of: thev acute angle. on the edges-10f thezsheeting will move -in'-' a .di;.

rection perpendicular to the line. of tangency;-

rather; than along the-.i'slope of theracute angle. Thus; each, successive-v point-ton an edge. of :"the sheeting ;Wil1iCIOSSIthC1iI18 of tangency at a dif:

ferent point" oni'such linei rather than at the same point: A. similar condition :exists .1 for any r point in the'sheetzwhich isrnotonan edge:there-'- of; Toaniobserver; this condition mal es..it.ap-

pear that the sheeting"as'. it1 passes between the.

rollsmoves acrcssithem...

The just-described condition must be" over come 1 if stretching operations of' the characters contemplated by this inventionzareto.=:-be:suc-= cessful'ly and practicably obtained; An answer to this problem is to cause the output or=discharge ofthei-olls to alwayssoccur. ata fixed:location or along: apredetermined sportion of the' li'ne of tangencyof the rolls. Discharge: at a-fixed -1ocation is. possible if .a force is introduced to: act

An electric motor 35, operatednby as For example, successive. pointer whichzis predeterminedly: positionediiandi'inclined; to:the:1ine ofjtangency of therolls. Anyway of. causing sheeting to track falls within the. concept.

of this invention.

A veryv satisfactory manner of. causing the.

sheetingito' trackin its movement as. effected by. two rotating rollsisto employ endless drivenbelt means comprising an individual belt engaged.

with each roll. In making use of; thisexpedient,

theb'elts. are wrappedaround therolls so that. their surfaces arexincontact and exert pressure:

along the line of tangency:betweenrthe rolls and the belts. It is also necessary that'thebelts move: in a direction which :is angularly disposed to the. lineof tangency-of the rolls at someangle other than 90, movement 10f the belts? referring par.-* ticularly to their movement in the zone. of contact and pressure between. the: belts and the wringer: rolls. It isdesirable thatthe surfaces of'the belts which contact. each. other develop considerable friction while the surfaces of the. belts which contact the rolls are as smooth and:

as frictionless aspossib'le.

By arranging the belts in this manner and by driving them, a force is exerted on the sheet -.driven belt to translatein a manner similar to that described in connection with the sheeting whichis being fed may be overcome by permitting slippage between eachbeltand its corresponding roll. Thus theabelts and thewringer rolls in combination with-each other provide feeding and tracking means whereby sheeting introduced between the rolls and'belts along a path predeterminedly positioned andinclined to the line of tangency therebetween willbe discharged therefrom along the same path.

Details of one convenient arrangement of belt means are disclosed inFig-s. 1,' 2' and'3, it being understood that various other arrangements may be employed without departing from'the spirit or the scope of this invention, the belt means functioning with the input rolls 43, 44 to move sheet material through and discharge the same from the inputsection of the machine'along a predetermined path;

The belt meansof the drawings comprises two endless belts '36'and 3'! arranged for movement over threesets of supports. Each support lies at a -corner-pf' a triangle. This arrangement of supports makes it possible to elfect movement of each belt 36 in a path which follows the sides of the triangle;

To carry out this-construotiomuse is made of two spaced pairs of "alignedrolls 38and 40 and 39 and ti respectively and a bank of aligned rollsr The roll bank comprisestheinput rolls 43 r and 44 between which sheeting 22 passes and also rolls i and dtlocate'drespectively above and belowrolls-43 and 44. All rolls 38 to 45 in the embodiment of Figs; 1,- 2 and '3 rotate about horizontal'axes. Rolls 38an'd-40 and rolls 39 and 4| are respectively supported in conventional manner upon plates stand 41, these plates being supply 23, is'also'supported on the-plate 46 while plate 4! supports a gear shaft 50 'havinga gear 49 which is-fixed thereon and which meshes with A rotatably =rotate "roll 4| when gear shaft 50 is driven from "the motor 35 in a manner to be later described. Rolls 38 to 41 are rubber or comprise a metal core encased in a rubber sheath and rolls 42 to 45 are formed of a suitable metallic material such 'as a chrome alloy and are polished.

As shown particularly well in Figs. 2 and 3, the belts 36 and 37 are arranged one above the other. Belt 36 goes around the roll 36, thence under and over the roll 43, then under and over the roll 39, then under and over the roll 42 and then back to the roll 38. The lowerbelt 31 goes around the roll 46, then over and under the roll 44, then 'over and under the roll 4| and thence over and under the roll 45 and back to the roll 46. In this arrangement, the parts of the belts 36 and 3'! extending at any instant between the rolls 42 to 45 and the pair of rolls 3% and 46 may be thought of as providing the incoming or sheet feeding branch of the input section of the machine while the parts of the belts between the rolls 42 to 45 and the pair of rolls 39 and 4| form an idler branch through which the belts 36 and 31 pass in their cycle of movement. Conventional pressure-applying means 5! are employed for pressing the rolls 33 and 4G and the rolls 39 and 4| together. With this con struction it will be appreciated that the belts 36 and 3'! will be continuously driven on actuation of the gear 49 to drive the gear 43 fixed on the shaft of the roll 4|. During a cycle of movement, a portion of either belt assumed initially at a position in the feeding branch will move therethrough, into and through the idler branch and back into --the feeding branch to its initial posih tion. The path of movements of the belts 36 and 31 may be traced by the arrows shown on the 'belts in Fig. 3. Suitably supported guides 52 shown in Figs. 1 and 2, may if desired be en- 'gaged with the edges of the belts 36 and 3! to insure tracking of the belts in the event slippage between rolls 42 through 45 is insufficient for this purpose.

In threading up the machine, sheeting 22 is led from the supply roll 23 and inserted between the belts 36 and 31 as they pass around the rolls 36 and 46 and'thence to the input rolls 43 and 44 and between the latter and the contacting surfaces of the belts which go around the same. With belt rolls 38 and 40 and input rolls 43 and 44 suitably pressed together, operation of the belts will result in continuously unwinding sheeting from the stock roll and feeding the same to the input rolls 43 and 44 in a direction lengthwise of itself and along a path which is predeterminedly positioned and angularly disposed to the line of tangency between the input rolls 43 and 44 and belting which passes around them, this path in the machine of Figs. 1, 2 and 3 being substantially the path followed by the belting thereof in the feeding branch of the belt means.

Belts 36 and 3'! are given substantially equal widths which are greater than the width of sheeting undergoing stretching and in the construction of the Figs. 1, 2 and 3 assist in maintainmg the sheeting in a substantially flat condition. However, as will hereinafter be pointed out,

while it is desirable to maintain the sheeting in a substantially flat condition, such requirement is not an essential. A conventional friction brake engaged to a pulley 53fixed to the shaft of the supply roll is employed to brake rotation 'of the latter so as to keep the sheeting 22 under slight tension as it is unwound from the supply roll.

A preferred'type of belt, especially adapted for use with sheet material which is rendered increasingly pliable with the application of heat thereto, comprises a belt having a smooth, substantially frictionless surface and a second or opposed surface which is yieldable and tacky. The tacky surfaces of the opposed belts frictionally contact and grip the sheet material as the belts and the input rolls 43, 44 function to feed or move it into the output section of the machine. In addition to these properties a preferred type of belt should also be flexible and resistant to heat and to stretching, that is to say, the belt should maintain its dimensions substantially constant under varying conditions of stress and temperature.

A portion of a belt of this type is shown in Fig. 6 and comprises a woven fibrous body 54 formed of cotton or other similar material. The body 54 has a layer 55 of a rubber compound such as neoprene formed on one surface thereof. The layer 55 is applied in coats and impregnates at least a surface portion of the body. In the formation of the layer 55, the body 54 is coated with a thin liquid coat of neoprene latex mixed with water to provide a water emulsion. A plurality of coats of neoprene latex of regular strength are then applied over the first coat of latex. Six coats of the undiluted latex have been found to provide an excellent type of surface for the purposes intended. I

A means for driving the belts 36 and 37 comprises a series of belts or sprocket chains E54, I55, I56 which connect a pulley or sprocket fixed on the gear shaft 50, two pulleys or sprockets 55 and 55' fixed on a vertical shaft 51, and driving and driven pulleys or sprockets 58 and 59 on a gear box 66, to .a pulley or sprocket 8! fixed 'on the drive shaft of the motor 35. The gearbox 66 permits the speed of the conveyor belts to be changed at will.

The sheeting 22 which is discharged from the .belt means 36 and 31 and input rolls 43 and 44 is received and engaged between the drawing or output rolls 26 which continue its lengthwise movement. The means for driving the output .rolls 26 comprise belts or sprocket chains 6i, 62

and 63 which connect a pulley or sprocket it! on one of the output rolls 26, pulleys or sprockets 64 and 65 on a shaft 66 carried by the frame of the table 20, and pulleys or sprockets 61 and 69 on a gear box 68, to a pulley or sprocket l6 fixed -on the drive shaft of the motor 35.

In the construction described, it is to be observed that the belt means 24 feed the sheeting 22 at an angle to the output section of the apparatus and always discharge it at the same lochange its path of movement. As already mentioned, it is desirable to apply pressure to the sheeting along the discharge line of the belt means'so as to permit the rolls 26 to'place the sheetin under a tension which is directed to stretch it. In the drawings, the discharge line is the line of tangency between the'belt rolls es and 44 and the belts which pass around them and is indicated by the reference numeral II in Fig. 4 while 12 indicates the line of tangency of the output rolls 26. Line H is also the line alon which pressure is applied to sheeting passing through the machine. It is to be noted that line H extends transversely across the path followed axis of the shaftof the belt roll -42.

agso ie-e i :by the incoming sheeting and is iinclined thereto.

Mounting means for each endxofrtheirolls 4.2 to .45 are .constructed so thatpressure may be :applied to themoving sheet materialrasiit passes .between rolls 43 and Malong the lineof tangency between the belt means passin over such rolls. One type .of mount isshown in Fig. Eran-d comprises a base :13 secured to the top f the table 20 and having .a pairof mounting posts '54 "extending therefrom and slidably engaged by hearing blocks 82,133, 384 and "85 which respectivelysupport an end of the'shafts 101' the rolls ".42, 43, M and 45. Bearing .block'185 seats upon spacers in the form .:of tubular collars lfiawhich are engaged on posts '54 and which'are seated .on the base 13. Spaced from bearing vbloclr85, by a'pair of tubular collars T'50nthe posts M, is the bearing 84. Each bearing block -83 .is engaged with posts It and has its associated roll contacting the roll carried by the bearing.-: lock '84 whereby each bearing blockis supported in the mannenillustrated. Tubular collars 5 .5, each engaged on apost l4 and supported by hearing '83,- .providea seat for bearing blockfiE.

Collars H on eachpostseat on the top'of bear- "ing block Bland support a plate 18 which is held on-the posts M by-nuts 19 on the-threadedends .of the posts -74. A pressure screw 80 extends through ,the plate l8 and isadapted to contact the bearing block 82 centrally thereof above the .By this constructionit will be appreciated that suitable :adjustment of the-screwim wi1l[cause pressure to be applied to the bearingblockBZ. This pressure will be transmitted through .thecollar 16 to the bearingrblock 83 which willcause the belt :rolls 43 and M .to be moved towards each other Land the pressure between them and the'belts to tially along the line of tangency-of the belts 36 and 3'5, to apply a frictional force to the surfaces of the incoming sheeting.

All of the belt rolls havebeen described as being rotatably mounted. It is tobe noted, however, that the rolls '42 to A5 inclusive may be 5 braked or locked so that they :remain stationary so long as the belting'readilyslides overthese rolls. Underthese conditions the rolls act as supports for the-belting.

As heretofore indicated, the forces set up in the sheeting ;in its movement through the two selected paths will cause the sheetin :to be stretched and at the same time :will orient the nnolecules of; the sheeting. .The physical ;mean :ing of "the angles a and "which angles deter-- mine 'the -paths along which-the sheeting. is moved when undergoing stretchin may be understood "with reference to thepmachine .of Figs.;.l,:2 and 3 :as Setup in the manner therein generally illustrated. As will presently. appear, "other machines :may be employed to carryout the invention. However, the physical meaning ofth-e input angle a andtheqoutputiangle 1/ used, in connection with the machine -..of Figs. l, .2 and 3;wi1l be-the .same for any :machine of .the invention.

fill

Iii

12 Movement :of the sheeting :throughsthe :machine of Figs. ,1, -2 and 3 is disclosed .in :the diagrammatic representation of the machine in Fig. Asmaybe observed in Fig. 4, .thewidt'h of the sheeting after stretchingis roughly equal to the hypotenuse ST of the right triangle RST shown in Fig. 4 of which the side BS is the original width of the sheet and the adjacent acute angle HST is equal to the angle through which the sheet isturned in following its path through the outputsection of the machine. The magnitude of the angle RST is of course dependent upon the position of the incoming branch of the belt means 24. Angie HTS which is the complement of the angle RST gives the angular relation of the incoming sheet material with respect to the output section of the apparatus. t may be here mentioned that while in Fig. 4 the width of thesheeting is increased by stretching, through the use of other practices it is possible to reducethe width dimension. Width dimension alterations of both types are included within the scope of the invention and further reference thereto will again be made.

Angle HTS is equal :to the acute angle "between the edge of the sheeting-opposite the edge RT and the line of tangency "H, this latter angle being called the input .angle a. 11 maybe defined as the an le theedge of the incoming sheet makes with the input rolls or withthe line of tangency between the input rolls and the belt 'means measured from a location ,facing the path in which the sheet'moves 'and-in ,a direction which is counterclockwise from 'an edge of such sheeting to extension of :the line 'of tangency ll, it being again noted that the .line of tangenc-y forms the discharge line of the input rolls and also that pressure is applied to the surfaces of the sheetinga'longthis line.

The line 72 in Fig. 4 represents the line of tanaency between the output rolls '26 and also a line along which pressure is applied to the sheeting as it is drawn by the output rolls. Since the axes of these rolls are parallel to the axes of the input rolls 4-3 and, the line 12 will be parallel to line H. The output angle may be defined as the angle which the outgoing sheet vmakes with the drawing rolls measured from a location facing that edge-of the moving sheeting from which a is measured and in a direction which is counterclockwise from-such edge to the .Means are providedin themachine of Figs. 1, 2 and 3 for; adjusting the beltmeans 2.4 so as to obtain 'apredetermined input angle a, the outtially maintained at 90?.

One construction permitting variation of the input angle mounts the belt rolls 38-and 4D and 39 and 4| on plates 48 and 4.1 which may be put angle in this embodimentbeing substanmoved over the-top of the table 29. The plates 46 and 2? are held in adjusted positionby fastening means 8'! such as removable bolts which secure them to the tabletop. To adjust the belt means 24, the fastening means 81 are loosened ;ably adjusted, the plates 46 and 4! are again secured to the top of table 20.

In the adjustment of the input angle, the feeding and the idler branches of the belt means 24 are positioned so that they still follow the sides of a triangle as previously described. Since the sprocket chain or drive belt I54 will pivot around its sprocket or pulley 46 on shaft 57 and the sprocket or pulley fixed to gear shaft 59, it will be apparent that the just-described adjustment of the belts 36 and 3'! may be readily effected.

It is to be understood that the adjusting means for the plates 46 and 41 may be varied in construction and arrangement. For example, plates 46 and 41 may be mounted upon tracks or guides and means involving the principles of the screw maybe used to effect desired movement of the plates or suitably actuated lever means may be employed for this purpose.

, In the, stretching of plastic sheet material by the practice described herein, there is a tendency for the molecules of the material to be nonuniformly oriented in a strip of the material which extends laterally from each edge of the sheeting for a short distance towards the center line of the sheeting. Between these edge strips, the molecules of the sheet material are substantially uniformly oriented. This nonuniform orientation along the edges of the sheeting is termed edge effects. Theoretically, these edge effects would be eliminated if there were no distance separating the drawing or output rolls 2% and the input rolls 43 and 44 in the vertical roll bank. It is therefore desirable to place the drawing rolls 26 as 'close to those in the vertical roll bank as possible. However, in some instances it is preferable to soften the sheet material before stretching it so as to facilitate its stretching. For example, it is desirable to soften sheet material which is difiicultly yieldable when in normal or hardened condition and which is liable to break or tear during stretching and which is rendered more ductile .;s

liquid or solution which will function solely to transfer heat to the sheeting. As an example,

thermoplastic materials are mentioned as materials which are preferably stretched when in a heated condition.

The solution of the problem of heating the sheet material while keeping the output rolls in close proximity tothe input rolls 43 and 44 is made possible by sheet-softening means 21 in the formof hot air distributing ducts shown in detail in Figs. 7 and 8, and comprising two narrow metal ducts 89 and 99, one located above and the other located below the path of travel of the sheeting in Each duct 89 and 90 is of a length which is greater than the .width of the sheet material 22 being processed .and extends across the path of material. 7

The ducts 99 and 90 are substantially similar and each may be formed of a hollow body portion travel of the sheet 9l joined to a pipeor conduit92 adapted to be 14 connected-to aheader 93 through which hot air from a suitable source, not'shown, is blown for distribution to the ducts. Pipe 92 is provided with a narrow slit or series of aligned openings 94 in the portion thereof which is joined to the body of its duct to permit heated air to be distributed throughout the body 9|. An elongated discharge orifice or slit 95 of a length substan-- tially equal to the length of the duct is provided in the end of the body 9| which is most distant from the conduit 92. this end of the body is bent so that the discharge of air from the body 9| takes place at an angle with respect to its entry into the duct body. The

ducts are positioned so that the discharge through their orifices 95 is directed entirely across the sheeting towards the discharge line or line of tangency between rolls 43 and 44 and the belts around these rolls, this line being indicated at H in Fig. 4. An important feature of the heating ducts 89and 90 besides their narrow bodies resides in their bent body portion which causes the heated air to be directed between the belts and concentrated onto the sheeting 22 as it discharges therefrom substantially along the discharge line of the belt means.

The temperature of the zone adjacent the moving material and between the rolls 43 and M and the output rolls 26 will indicate the degree to which the sheeting 22 is heated. In the case of plastic sheet material which is being stretched, it has been found that heating this zone to temperatures of from 80 C. to as high as 200 C. works excellently while a range of from C. to C. may be noted as the optimum tempera ture. Obviously, higher or lower temperatures .may be obtained in this zone by the use of conventional means for heating the air supplied to the zone. It will be appreciated that in general the kind of material, its thickness and the speed at which it is moved to the drawing rolls will influence the preferred heating temperature.

If desired, the sheeting 22 on discharge from the output rolls 26 may be wound or reeled up. :When the sheeting has been softened to facilitate stretching it may be preferable, especially in the case of certain thermoplastic materials, to reharden the sheeting under tension before either winding up or subjecting it to further processing. Rehardening under tension is particularly desirable in the case of stretched sheeting which is in a softened condition and which has a tendency to return to its original dimensions unless it is hardened under tension. In addition, it is desirable to have the stretched sheeting in as unyieldable condition as possible when it is subjected to further processing as, for example, when it is laminated to other sheeting, in order to avoid alteration of the properties imparted to the sheeting as a, result of the predetermined stretching thereof.

,, One practice for effectively hardening sheet materials which have been softened by heat makes use of an extended cooling zone located between the output rolls 26 and the laminating rolls 96 and 9'! shown in the machine of Figs. 1, 2 and 3 of the drawings. In this practice a plurality of rolls 28 are suitably mounted, as shown in Figs. 1, 2 and 3, upon the frame of the table 29 for rotation about axes which are substantially parallel to the axes of output rolls 26. The sheeting 22 .is passed over and under alternate rolls 28, suitable tensioning of the sheeting in the construction illustrated being effected by the laminating rolls 96 and 91- with which the sheeting is engaged. A

As shown in the drawings ascent hone provided by the rolls 7Z8 is'determ'ined by I the temperature to which the sheeting is to be heated, and is also influenced by the speed at w den the sheeting is 'to be run'throug'hthe cooling section;

Preferably; only that portion of 'the sheet whe'reinsubstantiallyuniform molecular orientation eceursis employed. "Hence, it is desirable to out awaythe edges of thesh'eet'wherein the edge enema-cater. Cutting ofthe sheet' is made posssiblebythe useo'f-cultting means 29. I

An alternate construction naking it possible to reduce the iength-of the cooling'Zoneis disclo'sed'in Fig. mwhereimheuse of only-one rel]. 28';is shown. Shortening of the 'coolin'gzone is effected through the use' of means E23 through which cold air is blown onto the shetin'g as it "leaves th'e output rolls 26. Means I 28'm'ay'comprise asuitableduct through which'cold airffrom a source of supply,"is"b-lown, or other coo1ing"de-' vice. i'iv'iththe construction of FigJfZa if desiredand "such additional means may be located on the same side of the sheeting as means [28 or on theopposite side of the sheet ng. v I v I Other cooling practices-m y be employed. For --example', cooling may be effected by suitable liquids or solutions used as baths or sprays "for 'the'softened or heated sheeting. Speaking generally, when employing agents in liquidfform for hardening sheeting; it is desirable 'to'use an agent wh ch will not be .a'ib's'orbed by "the sheeting-but which w ll enter into some reaction resulting in the sheeting'being hardened. "Such concepts fall within' thescop'eof this invention. 7 v

One suitable cutting'means comprises a pair of supports "98 which extendabove'the top of the table 253 on each side of thepath of the moving material'ZZ and support a ro11 9-9 and a reel-shaft 'ltt'between'them. Renee-and shaft I rotate about axes which are substantially parallel to the drawing rolls 2'5. "Reel shaft ili fl is dIfiVenal- "though roll .lilis-not. The cooled sheet material "22 in'it: passage through the machine 'passesfover the roll 99 and thence around a guide ro'll l0! to the laminating and drawing rolls ilfi and 9?. Sup: -ported from'the bearing blocks iorthe roll "99-is z'ahorizontalrod1'92 x'hich c'arri'e's'a'pair of razoredged knife means 183. Rod I02 extends across the path of theilm'oving material 'and'is-substam tially parallel'tothe various-roll axes. 'Thekn'ife means i 83 are adjustable longitudinally of the roll E1532 and are positioned between'the longitudinal edges 'of the sheeting 22 and in cutting nontact therewith rat a location in its path of movement between the last roll 28 and the roll 99 whereby to cut afstrip of predetermined width Efrem each side 30f the sheet material.

The main body portion of the sheet material 22 passes over'the roll 59 and' partially around the guide roll it! from which it pass'esto the drawing i'a ndilaminating rolls 95 and fi'l'while the cutaway edges we are engaged to and reeled upon the Ieelshaft 166. Means for driving thereel shaft :Hlfl, whichfservesas reeling mechanism for wind ing up thefcutfedges l fl i': of thesl'ieetin'g, comprises.

Additional-cooling means may be'employed heterogeneous.

pfiuey r sprocket r05 fixed onthe Shaft '65 and c'onnectedby a belt or sprocket chain HIS to' a pulley or sprocket ill! "fixed to the shaft H10.

After'the sheet material 22 has its edges cut away, it may be wound upon a roll or as shown in thedrawings it m'aybelaminated to a second "sheet material 3| to provide composite sheeting 34. The sheeting 3l is generally supplied in an unstretc'hed condition and is lamina-ted to the *sheeting 22 'for a number of reasons. Some materials, for example, certain plast c materials,

'tendto abso-rb'waterwith a'resultant change in their dimensions. A-change of dimensions may be expected to-counteraotthe effect-of stretching =and,at least'in' the case of stretchedplastic materials, render the orientationof the molecules Likewise, some materials if not stretched beyondthe elastic limit tend to return to their original shape or dimensions. Under such circumstances it-is hence generally desirable to laminate stretched sheet material immediately to other sheet material'asthe'bonded sheet ma terials will provide increased resistance to dimensio'nal change. Other reasons for laminating a second sheet'material to the stretched sheet 'material are-to protect the latter, at least on one side thereof, or "to provide a sup-port onto which still another layer of sheeting-maybe laminated or a support upon which'some material, for examplealight-sensitive emulsion, may be carried.

In carrying out the laminatng practice, the cut sheet material 22 'after'passage over roll I8! is drawn'between the rolls 96 and 91 which are held in pressure contact with each other. Roll -fi'irism'ounted for rotation about a horizontal axis 'an'd'is carried by'a fixed support wh ch extends above the top-ofthetable 20. Roll 91 iscarried by a frame Hi8 which is hinged as indicated at [89 to the frame of the table 20. When the roll 91is in its working position it rotates about a horizontal axis, which, like the axis of the roll 96, is substantially parallel to the axes of the other rolls in the output section of'the apparatus. Conventional means 'such as aspring device (not shown) are employed for retaining the rolls 9'6 and-:91 inc'ontact so that they will draw the sheet materials 22 and 3| lengthwise of themselves and into contact with each other on the rotation of the'rolls. The frame mounting I B8 is pivoted for convenience in initially introducing the two sheet .materials 22 and 3| between rolls 9% and 97. Sheeting 3! as already mentioned is obtained "from 'assupply 32.

The supply 32is carried by a roll H? rotatably 0 "supported upon'thetab'le for rotation about an axis which is'substanti'ally parallel to the axes of the' other rolls in the'output section of the apparatus. A'f'rictio'n brake I I8 is provided on the shaft of the roll H7 so as to keep the sheet- :ing 3! under tension. Roll 9t is driven from 'the.-.motor35 "through'the'gear box '58 in manner already described. Both of the rolls '96 and 9"! are' formed of rubberor they may "be constructedwith a metallic core which is covered "with a rubber sheath.

Forthepurp'ose of laminatingmater'ials which :mayfbe bonded together with a laminating agent, use islmade offa tank i it containing a suitable laminating fluid. Tank i ii) is positioned above the rolls s5 and ii? andis provided with suitable dispensing means, as shown'in the drawing, for dropping the fluid between the sheet materials 22 and '55 as they pass between these rolls.

The twozply laminated sheeting 34 may be "wound into a roll or it-may -be further processed.

asoame.

In the former case use is. made of winding mechanism 33 having a roll IIZ mounted for rotation about a horizontal. axis. which is parallel to. the other roll axes in. the outputsection. Roll IE2 is rcmovably mounted. upon a. shaft carried by the frame of the table 2.0. This shaft is driven by a pulley or sprocketwheel H fixed thereto and connectedv by a belt or chain I153 to a driven pulley or sprocket wheel I on the driven. shaft 66. For winding purposes; the. laminated sheet 3 3 before being connected to. the. winding roll I I2. is led partiallyaround guide rolls. HI which are carried by the frame of the table 2E! and which are freely rotatable about. horizontal axes. parallel to the axes of the other rolls in the output section of the machine. It will be. appreciated: that actuation of the motor 35 to drive the pulley or sprocket. 671 will cause. rotation: of theroll M2. to wind the laminated sheeting 34thereon.

Further processing of the two-ply laminated sheeting is instead. of. immediately Winding it into a roll may be beneficiaL. For example, where two plastic sheet materials are laminated to each other with. the aid. of a'laminating. or bonding fluid, it. may be desirable to subject the bonded materials to heat for the purpose of. hardening. the lamination. In this event, the two-ply sheeting 34. may be drawn through. a heat ng oven before it is wound While the supply 3-2 has been described as a single-ply sheeting, a roll of two-ply lamina-ted sheeting such as: sheeting. 34 may be mounted on the supply r011 II!- as a. variation ofthis practice. It is to be understood that the. supply rolls and the winding roll I I2 are-removably supported for the purpose of receiving, new material and for taking cfi. processed materiah Where twoply laminated sheeting is mounted. upon v thesupply roll I", it may be. led: off the roll and between the rolls 9.6 and 91 in a. manner to have either side thereof bonded. to the stretched sheet material 22.. In lieu ofthis: practice, stretched sheeting may be mounted upon the supply roll ill and laminated to sheeting which is also in a stretched conditions As a further variation, two machines may be positioned with the ends. of their output. sections adjacent each other. With such an. arrangement two-ply sheeting formed: byone. of. the machines may be led to the rolls 96- and. 9t of the second machine and directly laminatedtothe. stretched sheeting produced bythe. second machine;

Modifications in the structureof the machine are within the scope of invention. For. example, in the machine of. Figs. 1, 2. and. 3., sheeting i2 from the time it leaves the supply roll 23 until its dischargefrom the'dra-wing rolls 2s. is shown as movng in av substantially horizontal plane. Such practice need not necessarily be followed and a variation thereof is'shown in Fig. 9 of the drawing which illustrates aniodification of a portionof the machine. of Figs. 1, 2.and 3 suitable for effecting suchvariation, Fig. 9. being an. elevation of amodified machine. with. parts omitted and brokenaway and with partsin section corresponding, to the view.- off. the. machine shown inFig. 2.

The machine of Fig. 9' comprises a stand or table its adapted to. carry the various elements of the machine. shown mounted thereon abanl; of rolls comprising rolls I t2; 553', its and i iasupportedfromithe table in a manner simiiar to the rolls it? through 45 of Fig. Zbut havin their axes lying in a plane. inclined" to. the hori zontal or'to the'top ofthetabl'e' IZll; Belt means L24 corresponding to. belt means Mare employed. for feeding the sheeting in the manner described lengthwise of itself along a path which makes an angle with the line of tangency between the input rolls I43. and M4 and the belt means I24 in a. manner similar to that heretofore described in connection with the. belt means of Figs. 1', 2 and. 3-.

It is to be noted, however, that belt means [24. are generally inclined to the horizontal, sloping. upwardly from the supply roll for the machine ofv Fig. 9 (not shown) to the bank of rolls I42 through His. In the construction of Fig. 9- output or drawing rolls iii; are disclosed as suitably supported above the table top: I29 and. having their axes located below the axes of the input rolls I 23, and Hit. The sheet is drawn by the rolls I25 from the rolls Hi3, I44 downwardly to? wards the table top: The machine of: Fig. 9 is merely illustrative as it is apparent that variations therein whereby the supply roll of sheet.- ingi is at an elevation above the rolls I43; I44 and the output rolls I26 are locatedabove the input rolls M3, I'M are within the concept of: the invention.

In the machines heretofore described the belting in the incoming section of the belt means between the input rolls and the end belt rolls 38' and it is shown as having its adjacent surfaces more or less in contact throughout the incoming section. Such an arrangement is not essential. In fact the belts of the belt means 24- and I26 may be opened up, that is, spread apart from each other, the only requirement as to contact being, that they contact each other along the line of tangency between them andthe input rolls while they move in a predetermined direction as heretofore noted. Thus; any support afforded the sheeting being fed to. the input rolls by the belt means is more incidental. to the belt arrangement employed than. essential. However, as pointedout, contact between adjacent surfaces; of the belt means. assists, at. least to some extent, in feeding, the sheeting to the. input rolls in a substantially flat condition although feeding in this. manner is also not necessary to the operation. of. the machine.

The machines oflthe. invention will operate to stretch sheeting when the same is fed to and drawn from the input rolls in a wrinkled or in. a curved or in a folded. condition, or for that matter any condition other than a flat condition. Under thesecircumstances, however, the orientation or the sheeting will lack uniform character whereas uniformity of orientation is substantially obtained, except for the so-called. edge strips, when the sheeting is feed or moved: torthe input rolls. and is drawn therefrom in a' substantially fiat condition.

The machines which have. been described have shown the line of tangency between the input rolls: and belt means as substantially parallel. to the line of tangency oi the drawing rolls. An" arrangement whereby the line of tangency between the drawing rolls is angularly disposed to the line of tangency between the input rolls and belt means is within the concept of this inven-- tion. For example, and with reference-to Fig. I, the axes of the rolls 2% nd hence the line of tangency bet een them may be inclined to the axes of the 11* rolls, or in other Words to the tangent between the input rolls and the" belt means so that the line of tangencybetween rollsslopes away" from the line of t'angency between the input rolls and belt means in the plane of Fig. 1. The effect of such an arrangement is merely to provide an output angle '7 other than 90. In certain instances it may be desirable to have a' construction whereby the output angle 'y may be predeterminedly varied. An arrangement of this character is disclosed in Fig. 10.

Fig. is a plan view similar to Fig. 1 and shows a machine of the general construction of that disclosed in Figs. 1, 2 and 3 but suitably modified so as to permit adjustment to provide a variable output angle 7 as well as a variable input angle 'a. To effect this purpose, mechanism similar to that in the input section of the machine of Fig. 1 is employed in the input section of the machine of Fig. 10. Such mechanism comprises a bank 289 of four rolls, the upper roll being designated by the reference numeral 242 and the inner two of these rolls providing the input rolls of the machine together with driven belt means 224 which pass around the various rolls of the roll bank just described and also around suitable pairs 260 and 270 of belt rolls, each pair of belt rolls being mounted upon individual plates 246 and 241. The pairs of rolls 260 and 216 respectively correspond to the pairs of belt rolls 38, 40 and 39, 4| of Figs 1, 2 and 3. Plate 246 also carries a supply roll 223 having a supply of sheeting 222 mounted thereon.

Sheeting 222 from the supply roll 223 is fed to the input rolls of the roll bank 280 in the manner already described in connection with Fig. 1, its direction of movement being indicated by the dotted arrows 285 in the path traveled by the belt means 224 in the incoming section of the machine. Plates 246 and 241 are suitably mounted for adjustment and may be moved in the direction of the arrows adjacent each plate 241. Such adjustment efiects a change of the input angle a in the manner heretofore set forth. Rolls in the bank 280 are mounted by a construction providing means 225 similar to means of Figs. 1, 2 and 3 for applying pressure to the input rolls and belt means around the same so as to place'them in pressure contact.

The output section of the machine of Fig. 10 '5 differs from the output section of the machine of Figs. 1, 2 and 3 in that a vertical roll bank 300 comprising four rolls like those of the'roll bank 280 and the use of driven belt means 324 similar to belt means 24 and 224 are employed.

In the machine of Fig. 10 the middle pair of rolls of the roll bank 3% provide the output or drawing rolls for the device. Pressure-applying means 325 similar to pressure-applying means 225 and 25 are utilized for pressing the drawing rolls of the roll bank and the belt means into pressure contact with each other. The belt means 32 in addition to being supported upon the rolls of the roll bank 390 is carried upon two pairs 36% and 310 of suitable belt rolls which are mounted upon plates 3% and 3 11. Plates 346 and 341 are suitably mounted for adjustment in the direction of the arrows adjacent each plate so that the output angle 7 of the machine of Fig. 10 may be varied.

In the machine of Fig. 10, the outgoing sheet, that is the sheet material in the output section of the machine is engaged by the drawing rolls of the roll bank 395 and caused to follow a path indicated by the dotted arrows 385 on the belt means 32d. A driven take-off roll 354! winds up the stretched sheet as indicated. Roll 350 is driven by any suitable means, not shown for the sake of simplicity in the drawings. Likewise for simplicity. means for driving the belt drawings.

As shown in Fig. 10, the input angle a. and the output angle 1 both differ from With reference to definitions previously noted, the input angle of the machine as shown in Fig. 10 is less than 90 while the output angle thereof is greater than 90". It will be apparent that the belt means 324 may be arranged to provide an output angle 7 of 90, in which event the machine of Fig. 10 substantially duplicates the machine of Figs. 1, 2 and 3. It is also possible, in a construction like that of Fig. 10 to obtain an output angle 7 which is less than 90. Also to be noted is the fact that the output angle of the machine of Fig. 10 may be held at a value of greater than 90 and the belt means 22 adjusted so that the input angle a is substantially 90 as well as the fact that the machine may be adjusted so that the input angle a and the output angle 7 are equal to each other although for reasons which will presently appear a and 'y are not adjusted to give values having a sum of Roll banks 280 and. 30B are placed as closely together as is possible, heating means similar to those disclosed in connection with Figs. 1, 2 and 3 are mounted between the input and output rolls in. a manner similar to that heretofore described, such heating means being omitted for the sake of simplifying the drawings. If the belt means 324 are sufficiently long, the sheet in the output section of the machine of Fig. 10 will be sufficiently cooled by the time it reaches the wind-up roll 350 so'that no special cooling zone will be needed. However, if desired, a cooling section may be inserted between the pair of belt rolls 36B and the wind-up roll 350 as Well as means for cutting ofi the nonuniformly oriented edge strips of the sheet. Of course, the wind-up roll may be dispensed with and the stretched sheeting discharged from the output section of the machine of Fig. 10 may be led to laminating rolls and the other elements shown in the machine of Figs. 1, 2 and 3 for further processing.

Also contemplated within the scope of this invention is the successive processing of sheet material by several machines arranged in tandem or in series so that the output section of the first machine is adjacent the input section of the next machine and so on. By this practice, sheeting discharged from the output rolls of the first machine will be received and fed to the input rolls of the second machine and so on for the remainder of the machines in the series. An arrangement of this character will subsequently be described.

Other variations in practice, besides those just heretofore mentioned, are possible as will be well appreciated by those skilled in the art. It is to be understood that such variations are deemed to fall within the scope of the invention.

As previously pointed out, the process and apparatus of the invention are adapted for stretching a variety of sheet materials and are especially suitable for stretching plastic sheeting for optical, photographic and other purposes. The adaptation of the basic principles herein described to the stretchingof sheet materials which are thicker and less flexible or relatively more rigid than plastic sheeting is primarily one of constructing the stretching apparatus of a sulficiently sturdy and strong character to handle these materials. I

In addition, it will be appreciated that various elements of the apparatus forming the subject of tliis ihventiorr-may'ioeemeloveci-in other oroeesse es and with machinesother thaflthose' -lieretofore set" forth; Forexampl'e, the beit means which have been described in-connect ion W1 h ous machines are particularly suitablefor feed} i'ngjor moving sheet" materiallengthwise of' itself along a-predeteruiihediiiati'i and' ina F-lie employed fortfiis pur'oose in apparatus which will not stretch" sheetingi As an example, the belt means ma be used as an expedient or" apparatus for conveying sheeting; Likewise the helt means maybe" usedin conjunction with other types of sheet-stretching" apparatus; for'eiiamp sheet? stretching apparatus designed to: Stretch-O1 ere tend thesheeting length i'se itself-I that matter: it: will be apparentth e machines forming the'subje'ct of the" invent" may be ad justed so as to provide stretchingcftiiecharacteir fast mentioned: I p v For? optical; photographid and? illuminating purposes; trans arent plastic materials: iiavijue: longmhain molecules" may be employed for the sheetz'f. Transparent; hydrophilic; high molecular weight linear polymerswhici'i'may have tlieii molecules" oriented and which" are capabl'e' of forming a dichroic'sorpt'i'on complex-with ei'chroie stains and dyes are especially suitaiile when no iarized li'gl'iti involved" and specific" examples or these comprise polti' inyl alcohol; ools' h droxy aikar'ie partiallyhydroiyzedpolyvinylacetals'arrd? polyvinyl alcohol esters, amylose and? regenerated cellulose as well asisuitahli prep'aiied polyamides' or. nylon-type plastics: Of these materials;v poly? vinyialcoiioimayise menucriedas" rererreui The supporter protective sheeting which is laminated to the sheeting 223156 provide a twm ply; or com osite sheet material'- may be fbrmedofa cellui'osic plastic. Exam nes-oi such cellulbsic plastic comprise cellulose esters" such ascelliilbs'e acetateiaiidcellulose nitrate'orcellu'e. 4

lose mix'e'dTes'ter's' such asceiiuiose acetatebutw rate. or cellulose acetate eropiouate, or a vinyl compound} such as the vinyl acetatecfiloride copolymers. or a suitable condense tion-type superpolymer; as a suitahle polt amideor nylon-type plastic. 'Ilie" various types oriceilulbs'e esters such s s-cellulose nitrate and. cellulose acetate liutyiatei may be named as preferred transparent materials for the support. Suitably: prepared'cellulosic plas= tics mayalsoi be employed as. o tical elements themselves. For example, any, oil the cellulosic sheet materials just mentioned. may 'beap ropriatelyv stretched to provide a wave. retardation elementlusefiil; for: example, for varied optical purposes- Theisheeting 31' is suiicoated'witha suitable material, as. will be understood to the art, which will'lamihate directl'ir to one oftne materials namedifor use as the stretched sheeting, 2.21 preferafil'y, when? wetted withxwater; or a solvent) used as. a Laminating solution.

As it: hasyheen poixiteuout; the machines of the invention are adap ed to the prooessingzof continucus' sheet material; that'istcisay; sheeting iii extremist long, unbroii'e'e 6r uninterrupted lengths: Ebr. example, anyof, the elastic sheet materials; inst previously mentioned;. may be oht'ained iii rolls having lengths up to fiflmllfeet and greater. Rollsoftliis character Ina heei'npl'oyed astlie raw stockto beprocessed e machines described; herein. Material or su ntially, any width may be processed loysmaol'iihes of the verifie the maximuin- Widths of slie'etirig which upon the capacit (ift lfil'iiach ihf Plastic sheet a machine will? handle being dependent only materiais are obtainatieg ae resent; is maximum widths of around 30 inches and are also reeurabie in widths of as litiil'e as: se'veral inches: In" instances where relatively narrowcontiiiueusasheet ing is'd'e'sired"; as-"in'the case ofmot'ion -picture film, relatively wide processed sheeting comer-is ing a single-1ayer or a lamination-ofsev'eral layers may Ice-cut lengthwise of itself to form continu ousstrip's'o'f thedesired-wiiith'by theuse-of con ventional cutting means.

As anexample of a product produced by the xnachines of the'invention"; referenceis made td Fig: 18 which disclosesfilmmaterial lill suitaiile for'motion picture work andcomprising a supportlayer I 3"! formed ofan'y ofthe ment'ioned support materials; for-"example; celluloseacetate-butyrat'e; to opposite sides" of which there is laminated stretchedand oriented iniagecarrying layers i3? and liisofsheetmaterial such; for example; as polyvinyl alcohol} The orientation axes the layers I32 and F33 are at right angles toeach other and are inclined at an angle of45 "to" the longitudinal edges o'f'the film as indicated' by'the full lineand dotted arrows" in Fig. 18. Filmmaterial iBS iSadmirabiysuited for'the'formation of light-polarizing s'teres'copic" images therein, left e'ye images being formed in one-- image 'bearihg layer and' right -eye images-onlybeing-formed'inthe other image bearinglayer in the portionsthereofforming the successive frames of the filn'rmaterial;

Additional image bearin'g layers cf'thecharac= ter of layers strand i3i'super'posed' and' lamin ated on opposite sides of: the film material #33 5" permit the formation of light-polarizing color image components therein whereby to permit steresco'pic" reproduction in color. Alternatively, continuous film material may be provided" for the production of two-dimensional pictures By the use of a-supporthavinga single layer'thereon, or' a support having one'or more-layers on" the same oropposite side's thereof; these layers having' an orientation axis anguiarly disposed tothe longitudinal edgeof the film material and iii the case where severallayer's are used; orientation axeswhich are parallel to each other;

Light-polarizing images may be formed in oriented image-hearing layers which are" either Sensitive" or substantially insensitive to light liy methods well understoodto the art which effect the incorporation ofdicliroic'stains" and dies'in predetermihed portions of the layer; Lightpolarizirigiinagesof this character, namely; o'- tograp'h images; have an opticaldensity Whl is a function of" the vibration direction" of the incident lightused in'viewing or projecting such images: Film material we containing a ligiit= sensitive" suiista'nce may" have the same incor porated' in the im'agemarryingj layer thereof by im'hibition afterformation of the film or the light-sensitive material may be" cast" in the raw stock which is to be' stretched. In the latter instance, t 'vlestret'ching' is carried out under safe light conditions;

4 Lamination" of the several layers forming the film material rre may be carried out in the mariner. already described, for example; by laminating two-layer material formed. by: one machine' tos'iirgle-layer material discharged from a Second machine; I

Iti's believed that from the foregoing the op eration' of the processes and apparatus will be apparentespecially/when coupled with the fol lowing. explanation in regard: to stretching, 

